New York apartment buildings that permit smoking would be identified under a new law proposed Wednesday by Mayor Michael Bloomberg.

Landlords of buildings with three or more units would have to inform prospective tenants and purchasers whether smoking was allowed in apartments and on balconies, as well as in common outdoor areas like rooftops.

Bloomberg said this would give potential renters the chance to choose a smoke-free environment, free from wafts of cigarette smoke from other apartments.

"Smoking kills and people have the right to know if they are going to be exposed to secondhand smoke," Bloomberg said.

"We pursued this proposal in response to complaints from New Yorkers. It won't ban smoking in residential buildings, only ensure that New Yorkers can choose a smoke-free place to live."

The proposed law would be similar to requirements to disclose histories of bedbugs or lead paint, officials said.

Bloomberg is one of America's most prominent anti-smoking campaigners, extending a smoking ban from offices, bars and restaurants to parks and beaches.

The city has also raised taxes on tobacco in an attempt to price cigarettes -- now some of the most expensive in the United States -- out of reach.

According to the mayor's office, fewer than 10 percent of New Yorkers smoke at home.

"Even though the percentage of at-home smokers is small, in some buildings cigarette smoke can move quickly between apartments via cracks in the wall, ceilings and floors, through electrical outlets, and under doors," the office said.

"Air quality monitoring studies have detected elevated levels of harmful particulates in nonsmokers' apartments when occupants are smoking in another unit."